Plain concrete cloth bag pile suitable for karst area and construction method of plain concrete cloth bag pile

Abstract

The invention discloses a plain concrete cloth bag pile suitable for a karst area and a construction method of the plain concrete cloth bag pile. The plain concrete cloth bag pile comprises a geotextile bag body, and the top of the geotextile bag body made of synthetic fibers with certain strength is open; the multiple hoops are arranged on the periphery of the specific part of the geotextile bag body at equal intervals in the vertical direction; the distance between every two adjacent hoops ranges from 30 cm to 50 cm. The connecting part comprises connecting rods which are connected with the upper portion of the geotextile bag body and symmetrically distributed in the circumferential direction of the geotextile bag body. The multiple hoops are arranged on the periphery of the specific position of the geotextile bag body, plain concrete is wrapped with the geotextile bag body to form a composite structure with the outer bag and the inner concrete, the problem of pile body dispersion caused by karst cave slurry leakage can be solved, the pile forming integrity is improved, and unpredictable concrete over-filling amount and construction cost increase are avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bored pile construction in karst areas, and particularly relates to a plain concrete bag pile suitable for karst areas and a construction method thereof. BACKGROUND

[0002] Karst areas are generally characterized by poor geological conditions such as karst caves, soil caves and fissures, which bring many challenges to engineering construction. During the construction of traditional cast-in-place piles, problems such as concrete slurry loss and poor pile integrity often occur. At present, for karst areas with narrow karst caves, the corresponding karst treatment technologies include a steel casing wall protection method or a pre-grouting reinforcement method. The steel casing wall protection method has the advantages of less grouting loss and good pile quality, but has the disadvantages of high construction cost, large construction difficulty due to the need for segmented connection, and large disturbance to the foundation caused by the vibration of the steel casing. The pre-grouting reinforcement method has the advantages of filling the cave and preventing soil cave collapse, but has the disadvantages of uncontrollable grouting amount, high construction cost, and large disturbance to underground water flow.

[0003] Therefore, it is necessary to design a plain concrete bag pile suitable for karst areas and a construction method thereof to solve the above problems. SUMMARY

[0004] The present application aims to provide a plain concrete bag pile suitable for karst areas and a construction method thereof, which can flexibly adjust the bag structure according to the specific position and height of the karst cave, solve the problems of hole leakage and pile dispersion in karst areas, improve the pile integrity, and have the advantages of convenient construction and low construction cost.

[0005] To achieve the above-mentioned purpose, the present application provides a plain concrete bag pile suitable for karst areas, which comprises: A geotextile bag body made of synthetic fibers with a certain strength, the top of the geotextile bag body being open; A plurality of hoops are arranged at equal intervals along the vertical direction at the outer periphery of the specific part of the geotextile bag body to limit the lateral expansion of the corresponding position of the geotextile bag body; the distance between adjacent hoops is 30-50 cm; A connecting part comprising connecting rods connected to the upper part of the geotextile bag body and symmetrically distributed along the circumference of the geotextile bag body, so that the plain concrete bag pile is formed after grouting in the connecting part and the geotextile bag body.

[0006] As a further improvement of the present application, the tensile strength of the synthetic fibers is 20-50 kN / m.

[0007] As a further improvement of the present application, the cross section of the hoop is circular with a diameter of 8-12 mm.

[0008] As a further improvement of the present application, the connecting part top is connected with a casing facilitating fixation of the connecting part to the ground surface.

[0009] As a further improvement of the present application, the hoop is connected with the geotextile bag body through a plurality of connecting members arranged symmetrically along the circumferential direction of the geotextile bag body.

[0010] The present application also provides a construction method of the plain concrete bag pile suitable for karst areas, comprising the following steps: S1, excavating a pile hole and detecting the distribution of karst caves in the pile hole; S2, making the bag according to the distribution of the karst caves: a plurality of hoops are arranged on the geotextile bag body correspondingly, so that when the geotextile bag body is placed in the pile hole, the hoop corresponding part of the geotextile bag body can cover the area where the karst cave is located, and the top of the geotextile bag body is higher than the top of the karst cave; S3, fixing the top of the connecting part at the top of the pile hole, and placing and unfolding the geotextile bag body in the pile hole; S4, pouring concrete.

[0011] As a further improvement of the present application, the distance between the bottom point of the karst cave close to one side of the pile hole and the hoop below it is 1 / 2-2 / 3 of the distance between the two hoops above and below the bottom point of the karst cave.

[0012] As a further improvement of the present application, the distance between the top point of the karst cave close to one side of the pile hole and the hoop above it is 1 / 2-2 / 3 of the distance between the two hoops above and below the top point of the karst cave.

[0013] As a further improvement of the present application, the top of the geotextile bag body is higher than the top of the karst cave by more than 20 cm.

[0014] As a further improvement of the present application, the top of the geotextile bag body is provided with a connecting ring connecting the geotextile bag body and the connecting part.

[0015] The present application has the following advantages: 1. The present application sets a plurality of hoops on the outer periphery of the geotextile bag body at specific positions, forms a composite structure of "outer bag and inner concrete" by wrapping the plain concrete with the geotextile bag body, utilizes the characteristics of the geotextile bag body having certain strength and water permeability, can constrain the flow of concrete during pouring, solve the problem of pile dispersion caused by karst cave slurry leakage, and make the water produced by the hydration heat of concrete seep out through the pores, so as to make the concrete, the bag and the stratum tightly cemented, and improve the bonding strength of the plain concrete bag pile and the soil.

[0016] 2. The present application can avoid the problem of over-expansion of the geotextile bag body and the resulting damage to the bag body and leakage of grout by setting the geotextile bag body to be open at the top and using the concrete to press the bottom of the geotextile bag body during pouring, so that the part of the geotextile bag body corresponding to the hoop is offset from the area where the karst cave is located, and the geotextile bag body does not over-expand and cause damage to the bag body and leakage of grout.

[0017] 3. The present application can avoid the problem of leakage of grout by setting the top of the geotextile bag body to be higher than the top of the karst cave and using the filling of the concrete to make the top of the geotextile bag body tightly adhere to the soil.

[0018] 4. The present application can flexibly adjust the length of the geotextile bag body and the setting of the hoop according to the location and height of the karst cave, and does not need to set the geotextile bag body along the entire length of the pile, which is low in construction cost and easy to operate, can solve the problems of leakage of grout and dispersion of the pile body in karst areas, improve the integrity of the pile, and avoid unpredictable over-filling of concrete and increase in construction cost. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A structural diagram of a plain concrete bag pile suitable for use in karst areas.

[0020] Figure 2 A connection diagram of a hoop and a geotextile bag body.

[0021] Figure 3 A construction diagram of a plain concrete bag pile suitable for use in karst areas.

[0022] Figure 4 A deformation diagram of a geotextile bag body located at the bottom of a karst cave.

[0023] REFERENCE NUMERALS 10, geotextile bag body; 20, hoop; 21, lashing wire; 30, connecting rod; 40, steel casing; 50, karst cave; 60, guide pipe; 70, clamping point; 81, soil layer; 82, rock layer; 90, connecting ring. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be described in detail below with reference to the drawings and specific embodiments.

[0025] It should also be noted that, in order to avoid unnecessary details from obscuring the present application, only structures and / or processing steps closely related to the scheme of the present application are shown in the drawings, and other details not closely related to the present application are omitted.

[0026] It is also to be noted that the terms "comprising", "comprises" or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0027] As shown in Figures 1-3 The present application provides a plain concrete bag pile suitable for karst areas, comprising: A geotextile bag body 10 made of synthetic fibers with an open top; A hoop 20, a plurality of hoops 20 are vertically equidistantly spaced apart on the outer periphery of the specific part of the geotextile bag body 10 to limit the lateral expansion of the corresponding position of the bag body; the spacing between adjacent hoops 20 is 30-50 cm; A connecting part, including a connecting rod 30 connected to the upper part of the bag body and symmetrically distributed along the circumference of the bag body, so that after grouting in the connecting part and the geotextile bag body 10, a plain concrete bag pile is formed.

[0028] Specifically, the tensile strength of the synthetic fiber is 20-50 kN / m, so as to avoid excessive deformation of the geotextile bag body 10 at the corresponding karst cave 50 position during concrete pouring, which may cause damage to the bag body and lead to grout leakage, and to avoid low deformation of the bag body due to too high tensile strength of the geotextile bag body 10, which may affect the close fit of the bag body and the soil.

[0029] In this example, the tensile strength of the synthetic fiber is 30 kN / m, and the synthetic fiber is polyester.

[0030] Specifically, by limiting the spacing range between adjacent hoops 20, it can avoid the poor limiting expansion effect of the hoop 20 on the geotextile bag body 10 due to too large spacing, which may cause excessive expansion of the geotextile bag body 10, and avoid the increase of cost and inconvenience of transportation, construction, etc. due to too small spacing.

[0031] Specifically, the hoop 20 is made of steel and has a circular cross-section with a diameter of 8-12 mm, so that the geotextile bag body 10 can extend around the hoop 20 during concrete pouring, and compared with a square cross-section, it can avoid the stress concentration at the contact part of the bag body and the hoop 20 during the extension of the geotextile bag body 10, which may cause damage to the bag body. In addition, by limiting the diameter of the hoop 20, it can avoid the too small tensile strength of the hoop 20 due to too thin hoop 20, which may affect the limiting effect of the hoop 20 on the bag body, and avoid the increase of construction cost and the inconvenience of construction due to too thick hoop 20.

[0032] Specifically, the top of the connecting part is connected with a casing pipe for fixing the connecting part on the ground, and in this example, the casing pipe is a steel casing pipe 40.

[0033] Specifically, the hoop 20 is connected with the bag body through a plurality of connecting members arranged circumferentially symmetrically along the geotextile bag body 10. Figure 2 As shown in the figure, the connecting member is a lashing wire 21, which is used to fix the hoop 20 on the geotextile bag body 10.

[0034] As shown in the figure, the connecting member is a lashing wire 21, which is used to fix the hoop 20 on the geotextile bag body 10. Figure 3 As shown in the figure, the connecting member is a lashing wire 21, which is used to fix the hoop 20 on the geotextile bag body 10. S1, according to the drawing, the hole positioning of the plain concrete bag pile is carried out, the steel casing pipe 40 is buried at the hole, and then the rotary drilling machine is used to drill downward along the soil layer 81 to the rock layer 82 to obtain the pile hole; S2, the distribution of the karst cave 50 in the pile hole is detected; S3, according to the distribution of the karst cave 50, the bag is made: the geotextile bag body 10 is prepared by using synthetic fiber with a tensile strength of 20-50kN / m, a plurality of hoops 20 are arranged on the geotextile bag body 10, so that when the geotextile bag body 10 is placed in the pile hole, the hoop 20 corresponds to the bag body part can cover the area where the karst cave 50 is located, and the top of the geotextile bag body 10 is higher than the top of the karst cave 50; S4, the top of the connecting part is fixed on the steel casing pipe 40, the geotextile bag body 10 is placed in the pile hole and unfolded; S5, the pipe 60 for pouring concrete is placed in the geotextile bag body 10, and the concrete is poured.

[0035] Specifically, the distance between the bottom point of the karst cave 50 close to one side of the pile hole and the hoop 20 below it is 1 / 2-2 / 3 of the distance between the two hoops 20 above and below the bottom point of the karst cave 50. By limiting the distance between the bottom point of the karst cave 50 close to one side of the pile hole and the hoop 20 below it, even if the support of the soil body is suddenly lost during pouring, the geotextile bag body 10 will not suddenly deform greatly to contact the bottom point of the karst cave 50 and extend too much into the interior of the karst cave 50, and the bag at the bottom point of the karst cave 50 will not easily break due to stress concentration. That is, under the limitation of the soil body and the next bottom hoop 20, the deformability of this part of the bag body is relatively small, and even if it contacts the bottom point of the karst cave 50, it will not break due to excessive stress concentration at the catch point 70 in Figure 4 On the contrary, the existence of the bottom point of the karst cave 50 can also act as a limiting point, and together with the hoop 20, it can enhance the lateral pressure bearing capacity of the bag body.

[0036] Specifically, the distance between the top of the karst cave 50 near the pile hole side and the hoop 20 above it is 1 / 2-2 / 3 of the distance between the two hoops 20 on the upper and lower sides of the top of the karst cave 50, which has the same purpose as limiting the distance between the bottom of the karst cave 50 near the pile hole side and the hoop 20 below it, that is, to avoid the bag at the top of the karst cave 50 from being easily damaged due to stress concentration, and also to use the top of the karst cave 50 as a limiting point to work together with the hoop 20 to enhance the lateral pressure resistance of the bag body.

[0037] Specifically, the top of the geotextile bag body 10 is 20 cm higher than the top of the karst cave 50, so that the filling of concrete can make the top of the geotextile bag body 10 tightly fit on the soil, avoiding the occurrence of gaps between the top of the geotextile bag body 10 and the top of the karst cave 50, and causing problems such as slurry leakage.

[0038] Specifically, the top of the geotextile bag body 10 is provided with a connecting ring 90 connecting the geotextile bag body 10 and the connecting part. The connecting ring 90 can be replaced by a hoop 20 according to the actual construction situation. For example, when the distance between adjacent hoops 20 is set to 30 cm, and the distance between the top of the karst cave 50 near the pile hole side and the hoop 20 above it is 2 / 3 of the distance between the two hoops 20 on the upper and lower sides of the top of the karst cave 50, that is, the distance between the top of the karst cave 50 near the pile hole side and the hoop 20 above it is 20 cm, the connecting rod 30 can be directly fixed on the hoop 20 above the top of the karst cave 50 near the pile hole side. At the same time, the connecting ring 90 can also be set as needed, for example, when the top of the geotextile bag body 10 is 40 cm higher than the top of the karst cave 50 near the pile hole side, a separate connecting ring 90 is provided above the uppermost hoop 20.

[0039] In this example, in step S1, the pair of pile holes are dug out by a rotary drilling rig, with a diameter 50 mm larger than the designed pile hole diameter; In step S2, the geotextile bag body 10 is prepared from polyester with a tensile strength of 30 kN / m; the distance between adjacent hoops 20 is 30 cm; In step S3, the distance between the bottom of the karst cave 50 near the pile hole side and the lowermost hoop 20 is 1 / 2 of the distance between the bottommost hoop 20 and the second bottommost hoop 20, and the distance between the top of the karst cave 50 near the pile hole side and the uppermost hoop 20 is 1 / 2 of the distance between the uppermost hoop 20 and the second uppermost hoop 20; the top of the geotextile bag body 10 is 40 cm higher than the top of the karst cave 50; A connecting ring 90 is provided above the uppermost hoop 20 of the geotextile bag body 10.

[0040] The above examples are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalent replaced without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A plain concrete bag pile suitable for karst areas, characterized in that, include: The geotextile bag body, made of synthetic fibers of a certain strength, has an open top; Multiple ring hoops are arranged at equal intervals along the vertical direction on the outer periphery of specific parts of the geotextile bag to limit the lateral expansion of the geotextile bag at the corresponding positions; the spacing between adjacent ring hoops is 30-50cm; The connecting part includes connecting rods that are connected to the upper part of the geotextile bag body and are symmetrically distributed along the circumference of the geotextile bag body, so that a plain concrete geotextile bag pile is formed after grouting is performed in the connecting part and the geotextile bag body.

2. The plain concrete bag pile suitable for karst areas according to claim 1, characterized in that: The tensile strength of the synthetic fiber is 20-50 kN / m.

3. The plain concrete bag pile suitable for karst areas according to claim 1, characterized in that: The cross-section of the ring hoop is circular with a diameter of 8-12 mm.

4. The plain concrete bag pile suitable for karst areas according to claim 1, characterized in that: The top connection of the connecting part facilitates fixing the connecting part to the protective casing on the ground surface.

5. The plain concrete bag pile suitable for karst areas according to claim 1, characterized in that: The ring is connected to the geotextile bag body by multiple connectors symmetrically arranged along the circumference of the geotextile bag body.

6. A construction method for plain concrete bag piles suitable for karst areas according to claim 1, characterized in that, Includes the following steps: S1. Excavate pile holes and detect the distribution of karst caves within the pile holes; S2. Fabricate geotextile bags according to the distribution of karst caves: Set multiple rings on the geotextile bag body so that when the geotextile bag body is placed in the pile hole, the geotextile bag body part corresponding to the rings can cover the area where the karst cave is located, and the top of the geotextile bag body is higher than the top of the karst cave. S3. Fix the top of the connection part to the top of the pile hole, place the geotextile bag in the pile hole and unfold it; S4. Pour concrete.

7. The construction method for plain concrete bag piles suitable for karst areas according to claim 6, characterized in that: The distance between the bottom point of the karst cave near the pile hole and the ring below it is 1 / 2 to 2 / 3 of the distance between the two rings located above and below the bottom point of the karst cave.

8. The construction method for plain concrete bag piles suitable for karst areas according to claim 6, characterized in that: The distance between the apex of the karst cave near the pile hole and the ring above it is 1 / 2 to 2 / 3 of the distance between the two rings located above and below the apex of the karst cave.

9. The construction method for plain concrete bag piles suitable for karst areas according to claim 6, characterized in that: The top of the geotextile bag is more than 20cm higher than the top of the karst cave.

10. The construction method for plain concrete bag piles suitable for karst areas according to claim 6, characterized in that: The top of the geotextile bag is equipped with a connecting ring that connects the geotextile bag body to the connecting part.

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